This application claims the priority of Korean Patent Application No. 10-2005-0041765, filed on May 18, 2005 in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to a fluid mixing device for producing solutions with different concentrations of a sample solution and a diluent, and more particularly, to a fluid mixing device which produces a series of solutions with a concentration gradient with predetermined function from a plurality of channels by combining a sample solution and a diluent in a chip having a channel flow structure, without requiring a high electrical driving force.
2. Description of the Related Art
Generally, a fluid mixing device which produces a solution having a concentration gradient either produces an electrolyte solution having a various conductance (i.e., various concentration) used in an experiment for understanding dielectrophoretic properties of, for example, microparticles, or a series of sample solutions having concentration gradient such as a compound sample including a dye. In particular, producing a series of solutions with a concentration gradient by combining a sample solution and a diluent is called serial dilution, and a device which performs serial dilution in a chip is also known as a serial dilution chip.
An example of a conventional fluid mixing device which can be configured in a chip is a microfluidic device disclosed in “Microfluidic Devices for Electrokinetically Driven Parallel and Serial Mixing” (Anal. Chem., 1999, 71, 4455-4459). However, a high voltage in the range of 400 to 1,600 V is required for electrokinetic driving, and thus the microfluidic device cannot be applied to a portable lab on a chip. A microfluidic system disclosed in U.S. Pat. No. 5,869,004 uses electroosmosis, and thus additional devices and energy are required to apply a electric field to a microfluidic structure.
Other examples of conventional fluid mixing devices are microfluidic devices disclosed in “Generating Fixed Concentration Arrays in a Microfluidic Device” (Sensors and Actuators B 92,2003. 199-207) and U.S. Patent Publication No. 20010042712, which have a simple structure but take a long time to form a concentration gradient since it uses inter-diffusion of laminar flows.
A microchannel apparatus for mixing liquids using a microchannel disclosed in Korean Patent Publication No. 2003-0032811 has a relatively simple structure but has a problem that the series of solutions by serial dilution have a linear concentration gradient. This is a problem because an exponential concentration gradient is required in many cases for serial dilution.